This invention relates to improvements in or relating to liquid fuel burners for burning liquid fuel in gasified form having a fuel gasifying member for scattering the liquid fuel in atomized particles and producing gasified fuel, a combustion cylinder mounting the fuel gasifying member for rotation to permit combustion of the gasified fuel to take place in a combustion chamber, and a gas chamber formed along the inner wall surface of the combustion cylinder to supply the gasified fuel therethrough from the fuel gasifying member to the combustion chamber for combustion therein.
The present invention is concerned particularly with the provision of improvements in a liquid fuel burner of the type described so that ignition and combustion of the liquid fuel in atomized particles can be expedited, heating of the fuel gasifying member more than is necessary by flames of combustion of the gasified fuel can be avoided, the noise produced by combustion of the gasified fuel can be minimized, incorporation of liquefied fuel in the blue flames of combustion of the gasified fuel can be prevented when the burner shifts from combustion of liquid fuel in atomized particles to combustion of gasified fuel, and the liquid fuel can be supplied in uniform quantities to the fuel gasifying member to permit stable combustion of the gasified fuel to be sustained in the combustion chamber of the combustion cylinder over a prolonged period of time.
In the liquid fuel burner of the type described hereinabove, the combustion cylinder having the gas chamber formed along its inner wall surface is formed of thin sheet metal, and the fuel gasifying member is mounted for rotation in the combustion cylinder so that the burner may automatically shift from combustion of liquid fuel in atomized particles to combustion of gasified fuel. In this burner, it is necessary that the combustion cylinder and fuel gasifying member be prevented from being damaged by the flames of combustion or from being heated more than is necessary. If no means is provided for preventing these troubles, the combustion cylinder would be damaged by the flames of combustion and become unfit for further service at early stages of its use, the liquid fuel supplied to the interior of the fuel gasifying member would not spread along its inner wall surface in a thin fuel layer of even thickness but would drip through the interior of the fuel gasifying member, with a result that it would be impossible to gasify the liquid fuel in uniform quantities. In addition, red flames would be formed among the blue flames of combustion of the gasified fuel.
In order to eliminate the aforesaid troubles, I have developed a liquid fuel burner for burning liquid fuel in gasified form which includes an air ejection chamber formed in the combustion cylinder for ejecting cold air therefrom and causing a stream of cold air to flow along the inner bottom wall of the combustion cylinder, to prevent the combustion cylinder from being damaged by the flames of combustion. This burner is disclosed in U.S. Pat. No. 3,874,840.
The liquid fuel burner for burning liquid fuel in gasified form described hereinabove has since been found to have some disadvantages. First, the stream of cold air ejected from the air ejection chamber and flowing along the inner bottom wall of the combustion cylinder impinges directly against the flames of combustion of gasified fuel vigorously blown through gasified fuel blowing openings into the combustion chamber within the combustion cylinder. Thus the stream of cold air is prevented from flowing forwardly and stagnates in vortical flow along the inner bottom wall of the combustion cylinder. As a result, it becomes impossible to produce gasified fuel stably in uniform quantities and to prevent the formation of red flames among the blue flames when the fuel gasifying member is strongly heated to excess by the flames of combustion of gasified fuel
Secondly, since the combustion cylinder is not yet heated enough in the transition period in which the burner shifts from combustion of liquid fuel in atomized particles to combustion of gasified fuel following ignition of the liquid fuel in atomized particles, portions of the gasified fuel brought into contact with the inner wall surface of the combustion cylinder are liquefied, although small in quantity, and drip to the bottom of the combustion cylinder. The liquid fuel burns in red flames in the combustion chamber within the combustion cylinder or flows to outside therefrom.
Thirdly, a fuel diffusing member mounted in the interior of the fuel gasifying member is superheated by the heat of combustion at all times, and the liquid fuel supplied through a fuel supply line is repelled by the superheated fuel diffusing member to be changed into fuel drops. Thus it is impossible to obtain uniform diffusion of the liquid fuel and the fuel burns in an unsatisfactory condition, particularly when the fuel is of low quality, with residues of fuel being deposited on the inner wall surface of the fuel gasifying member.
Fourthly, difficulties are encountered in adjusting the quantity of liquid fuel supplied to the fuel gasifying member to obtain a satisfactory combustion condition in the liquid fuel burner for burning liquid fuel in gasified form in which the liquid fuel is supplied through the forward end of the fuel supply line disposed close to the outer circumferential surface of the fuel diffusing member so as to allow the liquid fuel to be diffused by the rotating fuel diffusing member into the interior of the fuel gasifying member which is also rotating. In this burner, the spacing between the forward end of the fuel supply line and the outer circumferential surface of the fuel diffusing member has an optimum value which may vary depending on the conditions including the viscosity of the liquid fuel, the pressure under which the liquid fuel is supplied, the angle of inclination of the outer circumferential surface of the fuel diffusing member and the number of revolutions of the fuel diffusing member. With the spacing being constant in dimension, the quantity of the liquid fuel supplied through the fuel supply line has very small upper and lower margins to be compatible with the dimension of the spacing. If the quantity were smaller than the lower margin, portions of the liquid fuel supplied would drip through the gap between the fuel diffusing member and the fuel supply line or leak along the outer circumferential surface of the fuel supply line. Even if it is desired to supply liquid fuel in a quantity larger than the upper margin, difficulties would be experienced in attaining the end because there is a limit to the opening of the fuel supply line relative to the outer circumferential surface of the fuel diffusing member. Thus the quantity of the liquid fuel that can be burned can only be controlled in a very narrow range.